Cutter suction dredge having parallelogram linkage wave compensator

ABSTRACT

A cutter dredge comprises a pontoon pivotally mounted on a spud driven into the sea bed, by means of a guide element vertically movable on the spud. The pontoon carries a cutter ladder pivotally on its end opposite the spud; and the lower end of the ladder is maintained at a predetermined elevation despite the wave motion of the spud and pontoon, by means of a parallelogram linkage having the pontoon as the lower side and having parallel sides upstanding from opposite ends of the pontoon and pivotally connected to the pontoon. The side of the parallelogram linkage at the cutter end of the pontoon is secured to the pontoon. The opposite side of the parallelogram linkage can be either a rod upstanding from the guide element, or a portion of the spud itself. The upper ends of the two upright sides are interconnected by a horizontal cable or stay.

United States Patent [1 1 Laarman [111 3,777,372 Dec. 11, 1973 [75] lnventor: Johannes Bertus Laarman,

Swijndrecht, Netherlands [73] Assignee: N.V. lndustrieele Handelscombinate Holland, Rotterdam, Netherlands [22] Filed: July 22, 1971 [21] Appl. No.: 165,125

[30] Foreign Application Priority Data July 22, 1970 Netherlands 7010848 [52] U.S. Cl 37/64, 37/72, 37/73 [51] Int. Cl E02f 3/88 [58] Field of Search 37/64-67, 73, 72

[56] References Cited UNITED STATES PATENTS 3,656,449 4/1972 Mead 37/73 X 3,579,872 5/1971 Jantzen 37/66 388,253 8/1888 Bowers 37/65 407,044 7/1889 Von Schmidt 37/65 3,253,357 5/1966 Allard 37/65 3,171,219 3/1965 Kaufmann et al. 37/67 X 3,470,633 10/1969 Soehnlen 37/67 2,917,851 12/1959 Ellicott, Jr. 37/73 826,096 7/1906 Ferris 37/73 UX 5/1890 Robinson 37/73 Primary Examiner-Robert E. Pulfrey Assistant Examiner-Clifford D. Crowder Attorney-Young & Thompson [57] ABSTRACT A cutter dredge comprises a pontoon pivotally mounted on a spud driven into the sea bed, by means of a guide element vertically movable on the spud. The pontoon carries a cutter ladder pivotally on its end opposite the spud; and the lower end of the ladder is maintained at a predetermined elevation despite the wave motion of the spud and pontoon, by means of a parallelogram linkage having the pontoon as the lower side and having parallel sides upstanding from opposite ends of the pontoon and pivotally connected to the pontoon. The side of the parallelogram linkage at the cutter end of the pontoon is secured to the pontoon. The opposite side of the parallelogram linkage can be either a rod upstanding from the guide element, or a portion of the spud itself. The upper ends of the two upright sides are interconnected by a horizontal cable or stay.

3 Claims, 1 Drawing Figure CUTTER SUCTION'DREDGE HAVING PARALLELOGRAM LINKAGE WAVE COMPENSATOR The invention relates to a cutter suction dredge comprising a pontoon which, by means of a pivotal guide element, at its stern embraces in a rotatable and vertically adjustable manner a spud to be driven into the floor of a body of water, and a cutter ladder pivotally mounted on the foremost end of the pontoon, the angular position of said cutter ladder being adjustable by devices provided on'the pontoon, which devices make it possible to control the operative depth of the cutter. A cutter suction dredge of this type is generally known in the art.

A disadvantage of these known cutter suction dredges is that while operating in turbulent waters the cutter will not always be kept in'its operative cut, i.e., the operative radius of the cutter dredger about the spud will vary, because of the vertical movements of the pontoon due to the wash of the waves or the swell.

It is an object of the present invention to provide a cutter suction dredge which is constructed such that even when operating in turbulent waters the cutter will always be kept in its operative cut. This object is achieved according to the invention by the fact that the cutter ladder, which is permitted to rotate freely, is connected with the spud by means of a parallelogram guiding arrangement.

The parallelogram guiding arrangement preferably consists of a first upstanding rod conncted at its lower end with the cutter ladder. The first rod is connected at its upper end with a second upstanding rod by means of an element which is pivotal at its junctions with the two rods. This second upstanding rod extends substantially parallel with the first rod and is connected with a guide element that rides on an upright spud, while the points at which the two rods are connected with one another are at the same elevation. A pontoon extends between the guide element and the lower end of the first rod.

The second rod may either be rigidly secured to the I guide element or may beform'ed by th'e'spud, or by'an extension thereof. In the'latter instance, the junction of the connecting element 6 with the rod 7 has to be vertically adjustable as well with respect. to the spud, while it has to be kept at a distance from the pontoon for instance by means of a rod.

With a cutter dredger constructed in the manner described above, the cutter will always be in its operative position even if the pontoon moves upwardly and downwardly or pitches. Thus, if the pontoon moves upwardly the cutter by its own weight will cause the first rod, and thus the second rod, as well, to be tilted through a given angle, as a result of which the spud will either be tilted directly or the guide element, connected to the second rod and embracing the'spud, will exert a bending moment on the spud, causing the spud to be tilted, so that the pontoon will move in the horizontal direction, which corresponds with the displacement of the cutter in the horizontal direction which would take place if there was a freely movable cutter ladder. I

The first rod forms preferably one side of a triangle which, in its normal position, extends upwardly, a second side of said triangle being formed by the cutter ladder.

Between the second rod and the pontoon there may be mounted an element, for instance a hydraulic jack,

. cutter ladder, the length of this element being adjustable, while the first rod is pivotally connected with the cutter ladder.

The invention will now be explained in more detail with reference to the drawing showing a diagrammatic view of a cutter suction dredge according to the present invention.

In the drawing is shown a pontoon l which floats on the surface of the water and to which is pivotally secured a cutter ladder'2, said cutter ladder terminating downwardly in a lower end which rests on the floor 3 of a body of water and which is comprised by a cutter element, not shown in the drawing. In the proximity of the pivot of the cutter ladder 2 there is provided a pivotally secured rod structure 4, the upper portion of which is connected with the lower portion of the ladder 2 by means of the rod or rope 5. Furthermore, the rod structure 4 is connected at its upper end with the upper portion of the rod structure 7 by a stay 6, which rod structure 7 is pivotally connected at 8 with the stern portion of the pontoon 1. Furthermore, there is mounted on the rod structure 7 an adjustable guide element 9, which embraces a spud 10 which is driven at its lower portion in the bottom 3. The arrow 11 indicates schematically the operationof a hydraulic jack, for instance, which is mounted between the pontoon and the-rod 7. If the pontoon starts to heave, i.e., starts to perform upward .and downward motions'parallel in itself, the entire cutter dredger will take the position shown by dotted lines in the drawing upon a given vertical movementof the pontoon 1. Owing to the fact that th'ecu'tter ladder 2 causes the rod structure 4 and thus the rod structure 7 as well, to be tilted to the left in the figure, if the pontoon l performs an upward movement, the guide element 9 is also tiltedresulting in the spud 10 being tilted to the left as well so that the pontoon 1 will accordingly perform a movement to the left in the horizontal direction. As a result of this the rod 4 will always extend parallel to the spud 10.

If the cutter has to be lifted or lowered to a further extent, the rope 5 is reeled in or paid out, it being understood that in this instance the position of the second rod structure has to be held fixed with respect to the pontoon.

By the present invention there is thus obtained a cut- I ter dredger structure in which the operative radius is the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

Having described my invention, I claim:

1. In a cutter suction dredger comprising a buoyant pontoon, an upright spud to be driven into the floor of a body of water, a guide element vertically movable on the spud, th guide element being pivotally interconnected with the stern of the pontoon, and a cutter ladder pivotally mounted on the other end of the pontoon; the improvement which comprises parallelogram linkage carried by the dredge, means maintaining said cutter ladder at a predetermined angle to one side of said parallelogram linkage, means maintaining the side of said parallelogram linkage opposite said one side para]- lel to said spud, said pontoon comprising a third side of said parallelogram linkage, the lower end of said one side of said parallelogram linkage being pivotally connected to said other end of said pontoon, a horizontal element pivotally connected at its ends between the upper ends of said one side and said opposite side of said parallel linkage, and means interconnecting the upper end of said one side of said parallelogram linkage and a portion of said cutter ladder remote from the pontoon.

2. A cutter dredge as claimed in claim 1, said horizontal element comprising a cable or stay.

3. A dredge as claimed in claim 1, and means to adjust the angle between said opposite side of said parallelogram linkage and said pontoon. 

1. In a cutter suction dredger comprising a buoyant pontoon, an upright spud to be driven into the floor of a body of water, a guide element vertically movable on the spud, th guide element being pivotally interconnected with the stern of the pontoon, and a cutter ladder pivotally mounted on the other end of the pontoon; the improvement which comprises parallelogram linkage carried by the dredge, means maintaining said cutter ladder at a predetermined angle to one side of said parallelogram linkage, means maintaining the side of said parallelogram linkage opposite said one side parallel to said spud, said pontoon comprising a third side of said parallelogram linkage, the lower end of said one side of said parallelogram linkage being pivotally connected to said other end of said pontoon, a horizontal element pivotally connected at its ends between the upper ends of said one side and said opposite side of said parallel linkage, and means interconnecting the upper end of said one side of said parallelogram linkage and a portion of said cutter ladder remote from the pontoon.
 2. A cutter dredge as claimed in claim 1, said horizontal element comprising a cable or stay.
 3. A dredge as claimed in claim 1, and means to adjust the angle between said opposite side of said parallelogram linkage and said pontoon. 